In before the swords are gain sentience and have humanoid form and the reason why they didn't return is that they still have not forgiven the former hero and demon king for losing them. Of course they are female.
When he started to call the swords and they didn't come right away, all I could imagine was them being far away and just cutting through everything in their path as they fly to his current location.
MOREEE pleasee I can't wait to know what will happen next. Anyway thanks for the update, please continue translating this manga really love it. Thank you translators.